The Imps have taken four points out of six off United this term but Alexander insists he is expecting two very difficult games.
Alexander told the Licnolnshire Echo: "We have won one and drawn one against them this season, but if I'm being honest I think we were fortunate in both games.
"If you look at their side they've got a bit of everything, and really I think they should have gone straight up.
"We did play very well in the second-half at their place, and as always we will be full of confidence.
"But out of the three teams we could have played, I would rather have avoided Scunthorpe."